Java中的WeakHashMap get()方法

WeakHashMap类的java.util.WeakHashMap.get()方法用于检索或获取在参数中提到的特定键映射的值。如果地图不包含该键的映射，则返回NULL。

语法:

WeakHashMap.get(Object key_element)

参数： 该方法接受一个对象类型的key_element参数，指的是应获取其相关值的键。

返回值： 该方法返回参数中key_element相关联的值。

以下程序演示了java.util.WeakHashMap.get()方法的工作方式：

Program 1:

// Java code to illustrate the get() method
import java.util.*;

public class Weak_Hash_Map_Demo {
    public static void main(String[] args)
    {

        // Creating an empty WeakHashMap
        Map<Integer, String> weak_hash = new WeakHashMap<Integer, String>();

        // Mapping string values to int keys
        weak_hash.put(10, "Geeks");
        weak_hash.put(15, "4");
        weak_hash.put(20, "Geeks");
        weak_hash.put(25, "Welcomes");
        weak_hash.put(30, "You");

        // Displaying the WeakHashMap
        System.out.println("Initial Mappings are: " + weak_hash);

        // Getting the value of 25
        System.out.println("The Value is: " + weak_hash.get(25));

        // Getting the value of 10
        System.out.println("The Value is: " + weak_hash.get(10));
    }
}

Initial Mappings are: {30=You, 15=4, 10=Geeks, 25=Welcomes, 20=Geeks}
The Value is: Welcomes
The Value is: Geeks

Program 2:

// Java code to illustrate the get() method
import java.util.*;

public class Weak_Hash_Map_Demo {
    public static void main(String[] args)
    {

        // Creating an empty WeakHashMap
        Map<String, Integer> weak_hash = new WeakHashMap<String, Integer>();

        // Mapping int values to string keys
        weak_hash.put("Geeks", 10);
        weak_hash.put("4", 15);
        weak_hash.put("Geeks", 20);
        weak_hash.put("Welcomes", 25);
        weak_hash.put("You", 30);

        // Displaying the WeakHashMap
        System.out.println("Initial Mappings are: " + weak_hash);

        // Getting the value of "Geeks"
        System.out.println("The Value is: " + weak_hash.get("Geeks"));

        // Getting the value of "You"
        System.out.println("The Value is: " + weak_hash.get("You"));
    }
}

Initial Mappings are: {Welcomes=25, 4=15, You=30, Geeks=20}
The Value is: 20
The Value is: 30

注意: 可以使用不同数据类型的变化和组合执行任何类型的映射相同的操作。